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Today's world of just-in-time inventory and zero defect expectations present new challenges to the manufacturing engineer. Final inspection is no longer considered an acceptable place to detect incorrectly built products, and many customers reject a complete shipment if even a single net is missing.

Syron Series SNP nut detectors use inductive proximity detection technology to sense the presence of a welded nut through a blind hole in sheet metal parts. This unique sensing probe develops a radial detection field to verify that the nut totally surrounds the probe and is properly positioned in its defined sensing area.

The all stainless steel probe resists weld splatter, and the sensing circuitry will not be damaged by the weld field environment. This allows the sensor to be used very close to the welding operation for detection of an incorrectly built part early in the assembly process.

The stainless steel probe tip resists abrasion allowing its use as a fixture gauge pin when used in conjunction with an optional sensor spring mount.

Syron offers a complete line of sensor spring mounts and output converter modules. We don't just provide a product; Syron provides engineered solutions.

System Components

A basic nut detection system consists of a sensor probe selected for the nut size being monitored, a cable assembly and a monitor module matched to the sensor probe and selected for either an NPN or PNP output.

Accessories

Sensor probe spring mount allows probe to retract when nut is out of place or hole is missing. Recommended for most applications. Catalogue No. SAB30403

Signal Converters Catalogue No. SSC24112 6 channel sensor interface box. Converts up to 6 NPN or PNP outputs to discrete 10 amp. 115VAC mechanical relay outputs for direct control of high power loads. Catalogue No. SSC24110 4 channel sensor interface box. Converts up to 4 PNP outputs to discrete 2 amp. 110VAC solid state relay outputs for direct control of high power loads. Catalogue No. 04392 5 channel "AND" gate converter box. Converts up to 5 NPN outputs to one NPN control logic output that only turns on when all used sensor inputs detect the presence of nuts. Eliminate power-up delays series select voltage drop sensors and it allows changes to the number of input sensors without rewiring.

Caution: The sensor probe temperature must not exceed 100ºC and it must not come into direct contact with the welding arc. Mechanical or pneumatic sensors can be used to extend the sensor probe to read and retract it during welding, or cooling air can be used.

Application Note
Thread Detection Using Series SNP Nut Sensor

Since its introduction in 1994, hundreds of installations have used Syron Nut Sensors to verify the presence of weld nuts in automated welding applications.

Two years ago, we found that the standard nut sensor system could be tuned to only provide an output when threads are present in the weld nut. This thread sensing capability has been expanded through field trial to include threads machined directly into sheet metal parts. One common new application is thread verification in progressive dies doing in-die tapping.

Component selection follows the same criteria that is used for nut detection. The probe and monitor are selected based on the thread size being checked.

Calibration follows these steps:

1. Insert probe into part that has threads. Rotate sensitivity adjustment potentiometer counter-clockwise until the load on/nut present light turns off. Slowly rotate clockwise until light turns on and stop rotating.
2. Insert probe into part that does not have threads. Rotate sensitivity adjustment clockwise counting the number of rotations. Stop rotating when the load on/nut present light turns on. Record the number of rotations required.
3. Divide the number of rotations by 2 and rotate the sensitivity adjustment counter-clockwise that number of turns

This calibration procedure sets the sensitivity halfway between sensing the part with threads and sensing the part without threads.

The result will be an output that turns on when threads are present in the part and no output if the threads are not present.